Electrically-wound clock



Jan. 6, 1931. R. H. wlLMl-:TH

ELECTRICAJLY WOUND CLOK Filed Oct. 4, 1926 Patented Jan. 6, 1931l UNITED STATES PATENT OFFICE ROSCOE H. WILMETH, OF SPRINGFIELD, ILLINOIS, ASSIGNOR T SANGAMO ELECTRIC COMPANY, OF SPRINGFIELD, ILLINOIS, CORPORATION OF ILLINOIS ELECTRICALLY-WOUND CLOCK Application led October 4, 1926. Serial No. 139,254.

motor, generally incorporated in the clock.

Heretofore, in clocks of this type, the customary method of controlling the motor, i. e., stopping and starting the same with the winding and unwinding of the` clock spring,

has been to open and close the motor circuit,

through switch mechanism made responsive to the tension of the main spring, or actuated by the winding and unwinding of the spring through a predetermined. number of turns. Electrical contacts requiring frequent opening and closingare always subject to pitting, arcin'g, etc., and hence these prior clocks have not been commercially successful, owing to the imperative necessity lof a clock giving reliability of' operation over indefinite periods of time, without serviceor attention.

The fundamental object of the present invention is to obviate the difficulties inherent in the use of electricalcontacts by providing an electrically wound clock in which the control exercised over the motor is in the nature of a mechanical braking thereof rather than an opening and closing of the motor circuit. Small motors of the inductiontype are now obtainable,- which will permit of braking down to a dead stall without injury to the motor and without any/'objectionable load fluctuation being imposed on the li'ne supplying the motor. Such motors can be slowed down, stopped and started indefinitely through braking retardation without deterioration of any of the working parts of the clock mechanism or motor.

A further object of the invention is to provide improved braking mechanism which will be sensitive in its action, to the end of keeping thwinding and unwinding limit-s of the clock spring within a comparatively small range, whereby an approximately uniform tension is always maintained on `the clock spring. The braking control forming the essence of this invention enables this tensional variation of the clock spring to be maintained between much closer. limits than is practicable in a clock wherein the motor circuit is opened and closed by Contact mechanism. Beca-use of the pitting and deterioration of the contacts in these latter types of electrically -wound clocks it is not practicable to open and close the motor circuit with the frequency required to obtain this close regulation of the clock spring tension. Such close regulation of the clock spring tension,

as obtained bythe present braking control, augments the time keeping accuracy of the clock.

Referring to the accompanying drawing illustrat'ing a preferred embodiment of my invention:

Fig. 1 is a front or face View of a clock movementv embodying the invention, the front mounting plate being broken away to illustrate part of the gear train;

Fig. 2 is a transverse sectional view taken on the plane of the line 2-2 of Fig. 1, the major part of the gear train being omitted from this ligure for clarity of illustration;

Fig. 3 is an axial sectional View through the main spring barrel and arbor of a modified construction, and

Figt is a detail sectional view taken on the plane of the line 4-4 of Fig. 3.

The clock movement may be of any prefer-red design or construction, the present invention being capable of embodiment in practically any type of movement with very little modification of standard construction. As exemplary of a typical construction of-cleck, I have shown in Figs. 1 and 2 a design wherein the gear train, main spring &c., are all mounted in a frame structure comprising front and rear disclike plates 8 and 9, held in spaced relation by posts l1. The minute hand (not shown) is carried on a central arbor 12, and the hour hand is supported on a sleeve 13 which is connected to the minute hand arbor through the usual speed reducing gearing 14, as is typical of conventional clock practice. Theelectric motor 15, which winds the main spring, is preferably mounted on the outer side of the rear plate 9, the frame of the motor having extending lugs 17 which are secured to spacing posts 18 by screws 19.

This motor is preferably of a small induction an ordinary lighting circuit. The armature shaft 21 of the motor extends through the back plate 9 and carries a small pinion 22 which meshes with a relatively large gear 23 on an arbor 24 pivoted between the end plates. The pinion 22 and gear 23 are preferably located in close proximity to the back wall 9, the large gear 23 constituting the rotating element to which the braking retardation is applied, as will hereinafterappear.

The reduced speed of the arbor 24 is transmitted through a pinion 25, mounted on this arbor, to a large gear 26 mounted on a second arbor 27, also journaled in the end plates 8 and 9. A pinion 28 mounted on this second arbor transmits the reduced speed thereof to a large gear 29 mounted on a third arbor 31, also journaled at its ends in the front and rear plates. On this third arbor is a pinion 32 which meshes with a large gear 33 which is pinned to the main spring arbor 34. The second and third arbors 27 and 3l, together' with their respective gears, have been omitted from Fig. 2 to avoid obscuring the illustration of the braking mechanism. As shown in Fig. 3, the main spring 35 and spring barrel 36 are mounted on the main spring arbor 34, preferably adjacent the back plate 9, the spring barrel being freely rotatable on the arbor. Such arbor comprises a threaded portion 37 over which screws a collar 38 having a flange 39 extending radially therefrom. Two or more pins. 41, having riveted attachment to the adjacent wall of the spring barrel, extend through holes 42 in the flange 39, these pins compelling the threaded collar to rotate with the spring barrel, but permitting the collar to screw back and forth along the thread '37. The forward end of the collar is formed with an'annular groove 43, and engaging in this groove is a forked end 48 of a lever 48. This lever extends transversely through the various parts of the gear train before described, for pivotal mounting at 49 on a post 51 extending forwardly from the back wall 9 at a point adjacent the gear 23 and arbor 24. As shown in Fig. 1, the pivotal mounting of the lever 48 on the post 51 is preferably eEected by forking this end of the '.lever to embrace the post and to receive a p1vot pin passing through the lever and post. Adjacent its pvoted end the lever carries an adjustable screw member 53 having a threaded portion 54 screwing through a tapped hole in the lever. The inner end of .this screw is adapted to bear against a braking surface 55 rotating with the gear 23. This braking surface 55 may be the actu al side of the gear, but preferably it consists of a disc of fiber or some similar material secured to the gear.

The inner convolution of the mainspring l35 is secured to the arbor 34, as by a pin or key 44, and the outer convolution is suitably secured to the spring barrel 36, whereby the tension of the spring operates to rotate the spring barrel, and also the ring gear 45 which extends from the periphery thereof. This ring gear meshes with a pinion (not shown) mounted on the minute hand arbor 12. Any suitable escapement mechanism 4G is operatively connected to the minute hand arbor through a suitable gear train, not shown.

In the operation of the clock, the energization of the motor l5 will drive through the gear train previously described, which will operate to impart a slow speed winding rotation to the main spring arbor 34. As this arbor is winding the main spring it is also revolving the threaded portion 37 within the threaded collar 38. With tension existing in the spring 35 the spring barrel will, of course, be rotating in the same direction as the arbor 34, but the rotation of this spring barrel, and hence of the collar 38, will be so slow that the collar may be considered as remaining practically stationary. Hence the rotation of the threaded portion 37 of the arbor Within this collar will result in the coilar moving inwardly along the arbor, the threads having this direction of lead. As the spring approaches the desired limit of its winding tension, the end shoulder of the groove 43 gradually swings the braking lever 48 backwardly. This will bring the end of the screw member 53 against the brakingface on the gear 23, exerting a gradual braking retardation thereon until the motor ceases or substantially ceases rotation at the point where the desired winding tension has been given 'the spring 35. With the main spring arbor 34 inert, or substantially inert, as the .result of the aforesaid braking action, the continuedrotation of the 'spring barrel 36 will gradually screw the threaded collar 38 back along the threaded portion 37 of the main spring arbor. When the spring barrel has revolved through a given angular distance, corresponding to the lower predetermined limitv of its spring tension, the other shoulder of the groove 43 will have swung braking lever 48 back to a position removing the braking friction of the screw 53 from the brake surface 55. Accordingly, the motor 15 will be permitted to resume rotation, with the result that the main spring will again be Wound to a. predetermined tension through a repetition of the cycle previously described.

The relative screw threaded motion for imparting swinging movement to the brake lever can be obtained through equivalent coacting parts disposed at some different point in the gear train, or operatively connected to the gear train. Similarly, the location of the moving brake surface 55 need not be confined to the gear 23, as this braking effort might be applied to a braking surface carried directly on the armature shaft 21 or on either of the other arbors 27 and 31. Certain distinct advantages, however, accrue to locating the screw-threaded elements and the braking elements substantially as shown in Figs. 1 and 2. The main spring arbor 34 is a slowly rotating, high torque element enabling a slow movin force of large moment to be applied to the' raking lever. The braking surface 55 on the side of the-'gear 23 revolves at a relatively high speed, but with little torque, and hence the braking eort applied thereto controls the rotation of the motor to a nicety. By applying the braking retardation to a brake surface on the arbor 24, rather than on the armature shaft, the latter is relieved of the end .thrust incident to the braking operation.

Through adjustment of the screw 53 in its threaded mounting in the lever 48, the upper limit of the working spring tension can be shifted to any desired point in the total range of spring tension.

In the modied construction shown in Figs. 3 and 4, the same driving relation exists between the electric motor l5 and the large gear 33 on the main spring arbor 34. However, in this embodiment, the braking action occurs at the spring barrel end of the driving train, rather than at the motor end of the train. One wall of'the spring barrel is formed with an axial hub 57 which is threaded externally at 58 to receive a threaded collar 59. A iange 61 extending from this collar has longitudinally extendin riveted therein. These pins exten through holes 63 in the arbor driving gear 33, whereby the collar 59 is compelled to rotate with the gear 33, but is permitted to move axially along the threaded hub 5 7. Projecting from ther front plate 8, or from any other suitable support, is a bracket 65 in which is pivoted at l 66 a pawl or stop member 67 The nose 67 of this pawl is disposed at a point to be engaged by one of the pins 62 when the collar 59 is threaded outwardly along the-hub 57 toa predetermined degree. The pawl 67 has a yieldable braking action on the pins 62 by virtue of a spring 68 connecting to a laterally extending arm 69 of the pawl. This spring normally holdsthe nose 67' of the pawl in position to be engaged by the pins 62, as above described.

In the operation of this embodiment, the winding rotation transmitted to the arbor 34 will result in the collar 59 screwing outwardly along the hub 57 of the spring barrel. When the spring has been wound to a predetermined tension, or through a predetermined angular distance, one of the pins 62 strikes the nose 67 of the-pawl, thereby gradually reducing the speed of rotation of the arbor 34 through the resilient pressure of the pawl and inally bringing the arbor to a dead stop. As the spring barrel-continues with its forward rotation in the unwinding of the spring, the collar 59 will be screwed Vinwardly along pins 62 the hub 57 until the pin 62 clears the end of the pawl 67. Thereupon, the driving rotation to the arbor 34 will again be resumed, until the spring has been wound to its predetermined maximum tension, whereupon the lpreviously described braking action Willagain occur.

In the event of the source of current to the motor being interrupted, in either of the preceding embodiments, the reserve tension of the main spring 35 will be sufficient to con tinue the operation of the clock for a considerable period of time. As soon as current again comes back on the line, the motor will rewind the main spring to its previous working tension.

What I claim as my invention and desire to secure by Letters Patent` is l. In an electrically wound clock, the combination of a clock spring having an arbor and a spring barrel, an electric motor, a gear train connecting said electric motor with said arbor, brake mechanism comprising a relatively high speed rotating brake surface associated with said gear train adjacent the motor end thereof, a thread on said arbor, a threaded collar screwiingr over said arbor, pins projecting from said spring barrel and engaging in holes in said threaded collar, a lever adapted to be moved bythe longitudinal threading motion of said collar for actuating said brake mechanism, and a member adjustably mounted on said lever and adapted to engage said brake surface.

2. In an electrically wound clock, the combination of a main spring having an arbor and a spring barrel connected to opposite ends thereof, an electric motor, a gear train operatively connecting said electric motor with said arbor, brake mechanism associated with said gear train adjacent to the motor end thereof, inner and outer screw members connected with said arbor and said spring barrel` said outer screw member having longitudinal threading motion along said inner screw member., andv a lever for transmitting the longitudinal movement of said outer screw member to said brake mechanism.

3. In an electrically wound clock, the com- 4 bination of a clock spring having an arbor and a spring barrel, an electric motor, a gearv spring barrel, said collar having longitudinal screwing motion along the thread on said ar-' bor, a lever for transmitting the longitudinal motion of said collar to said friction brake mechanism, and means for adjusting said brake mechanism.

4. In an electrically wound clock, the combination of a clock springgan electric motor, a gear train operatively connecting said electric motor with said spring, a rotating brake surface associated With the gear train adjacent to the motor end thereof, inner and outer threaded members screwing together, one of said members being connected to revolve with one end of said spring, the other mem.- ber being connected to revolve with the other end of said spring, said outer threaded mem'- ber being` caused to shift endwise bv relative rotation between said members, a lever actuated by the shifting of said outer threaded member, and a brake member adjustably mounted on said lever and adapted to bear againsty said friction surface.

5. In an electrically Wound clock, the combination of a main spring arbor, a main spring coiled about said arbor and having one end connected thereto, a rotatable driven member disposed coaxially of said arbor and connected to the other end of said main spring, an electric motor, a gear train operatively connecting saidmotor to said arbor to Wind said spring y therethrough, a friction brake surface associated with the gear train adjacent to the motor end thereof, inner and outer threaded members screwing together,

one of said members being connected to re- .Volve With said arbor and the other being ccnnected to revolve with said driven member, said outer threaded member being caused shift endwise by relative rotation between said members, a lever actuated by the shifting of said outer threaded member and a member adjustably connectedI with said lever and adapted to bear against said friction surface.

6. In a motor wound clock having a driving ,spring attached `at one end to a spring barrel and at the other end to a spring arbor and a gear train connecting the drive shaft of the motor of the clock With the arbor, the combination of a collar threaded on said arbor, said collar having transverse holes and a circumferential recess, pins fixed to said spring barrel and extending into said holes, a lever pivoted on one end and riding in said recess at the other end, a friction disk secured to one of the gears of said train, and a pin member adjustably connected to said lever between the ends thereof and adapted to bear against said friction disk.

ROSCOE H. WILMETH. 

